Check valve and fuel tank with check valve attached thereto

ABSTRACT

A check valve attached to an inner wall of a main body of a fuel tank ensures a sufficient seal of the main body from outside, without increasing the required number of parts. The check valve communicates with a fuel conduit of a fuel inlet pipe and functions to prevent liquid fuel and fuel vapor in the main body from flowing through the fuel inlet pipe and being released to the outside. The check valve is opened by a flow of fuel in the fuel inlet pipe and allows the flow of fuel to be introduced into the main body. The check valve includes a casing with a fuel outlet, a valve disc, and a fixation plate. The valve disc is movable between an open position and a closed position to open and close the fuel outlet of the casing. The fixation plate has one end inserted in an end of the casing and the other end welded to the main body. This arrangement enables the main body to be securely sealed from the outside.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to fuel tanks having a check valveattached thereto, and more particularly, a check valve attached to amain body of a fuel tank.

2. Description of the Related Art

In a fuel tank of an automobile, a check valve is attached to a mainbody of the fuel tank in order to prevent liquid fuel and fuel vapors inthe main body of the fuel tank from flowing back and being released tothe outside during fueling. A conventional check valve has a rathercomplicated structure to attach the check valve to an inner wall of themain body of the fuel tank.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a check valve havingsufficient sealing properties with a simple structure as well as toprovide a fuel tank with the check valve.

At least part of the above and the other related objects are attained bya first check valve that is attached to an inner wall of a main body ofa fuel tank. The first check valve includes a casing having a fuel inletand fuel outlet through which a supply of fuel is ejected from the valvecasing to the main body; a valve disc for opening the fuel outlet onlywhen sufficient fuel pressure is applied to the valve disc from the fuelinlet pipe; and, a fixation plate surrounding the casing and having aninner end and an outer end for hermetically sealing the main body. Theinner end of the fixation plate is inserted through insert molding intoan end of casing, and the outer end is arranged to be welded to theinner wall of the main body.

The first check valve of the present invention, which is attached to theinner wall of the main body, is set to the open position by a flow offuel injected through the fuel inlet pipe, and accordingly, enables theflow of fuel to enter the main body. When no fuel is supplied, the valvedisc of the check valve is kept in the closed position to close the fueloutlet of the casing, and thereby, prevent the liquid fuel and fuelvapors in the main body from flowing back and being released to theoutside.

The check valve is attached to the inner wall of the main body via thefixation plate by welding. The fixation plate has an inner end insertedthrough insert molding into the main body. The fixation plate seals themain body from the fuel inlet pipe and the outside, thereby specialsealing elements, such as O rings, are not required and reducing thetotal number of parts.

Having the fixation plate, which is inserted through insert molding intothe end of casing, integrated with the casing simplifies the process ofattaching the check valve to the main body.

In accordance with one preferred embodiment of the present invention,the flange of the casing has a ring-shaped seal projection that isprotruded to surround the fuel outlet. The ring-shaped seal projectionis pressed against and jammed to a side wall of the main body, therebyensuring a seal of the main body from the fuel inlet pipe. This simplestructure enhances the seal between the flange and the side wall of themain body.

It is preferable that the fixation plate has a handle, which is arrangedon a circumference thereof to hold the check valve during attachment ofthe check valve to the main body. The hold facilitates the attachment ofthe check valve to the inner wall of the main body.

It is also preferable that the check valve include a spring that pressesthe valve disc to the closed position.

In accordance with another preferred embodiment of the presentinvention, the casing has a seat, and the valve disc includes a valveelement that is seated on the seat in the closed position and removedfrom the seat in the open position to close and open the fuel outlet; anarm linked with the valve element; and an attachment that is connectedwith the arm and is formed to attach the valve disc to the casing. Thevalve element, the arm, and the attachment are integrally formed from athin plate having elasticity. The arm is designed to press the valveelement against the seat to cause the valve element to be seated on theseat in the closed position. The arm causes the valve element to beremoved from the seat and thereby sets the valve element in the openposition when the valve element receives a pressure of a flow of fuelapplied thereto at a time of fueling.

The present invention is also directed to a first fuel tank including amain body, in which fuel is kept, and a fuel inlet pipe, which isconnected to the main body and through which a supply of fuel is flowninto the main body. The first fuel tank is provided with a check valvethat is attached to an inner wall of the main body and is connected to afuel conduit of the fuel inlet pipe. The check valve prevents liquidfuel and fuel vapors in the main body from flowing through the fuelinlet pipe and being released to outside. The check valve is opened by aflow of fuel in the fuel inlet pipe to allow the flow of fuel to beintroduced into the main body. The check valve includes a valve chestconnected to the fuel inlet pipe; a casing with a fuel outlet, throughwhich a supply of fuel is ejected from the valve chest to the main body;a valve disc that is movable between an open position and a closedposition, so as to open and close the fuel outlet; and a fixation platethat is formed to seal the main body from outside and fix the valve discin the main body. The fixation plate has one end inserted in an end ofthe casing, which forms a flange, and the other end welded to the innerwall of the main body.

The arrangement of the first fuel tank facilitates the attachment of thefirst check valve to the fuel tank.

The present invention is further directed to a second check valve thatis attached to an inner wall of a main body of a fuel tank, in whichfuel is kept, and that is arranged in the vicinity of a fuel outlet of afuel inlet pipe, through which a supply of fuel is ejected into the mainbody. The second check valve includes a fixation member that has a seatdesigned to surround the fuel outlet and is formed to fix the checkvalve to the inner wall of the fuel tank; and a valve plate that isattached to the fixation member and is movable between an open positionand a closed position to open and close the fuel outlet. The valve plateincludes a valve element that is seated on the seat in the closedposition and removed from the seat in the open position, so as to closeand open the fuel outlet; an arm linked with the valve element; and anattachment that is connected with the arm and is formed to attach thevalve disc to the casing. The valve element, the arm, and the attachmentare integrally formed from a thin plate having elasticity. The arm isdesigned to press the valve element against the seat to cause the valveelement to be seated on the seat in the closed position. The arm causesthe valve element to be removed from the seat and thereby sets the valveelement in the open position when the valve element receives a pressureof a flow of fuel applied thereto at a time of fueling.

In the second check valve of the present invention, the valve plateattached to the fixation member is movable between the open position andthe closed position in order to open and close the fuel outlet of thefuel inlet pipe. The valve plate is made of a thin plate havingelasticity and includes the valve element, the arm, and the attachment,which are integrally formed. The valve plate is attached to the fixationmember by means of the attachment, which is linked with the valveelement via the arm. The arm functions as a spring that applies apressing force in the direction of seating the valve element onto theseat. When the valve element receives a force of a flow of fluid appliedthereto, the arm inclines the valve element to open the fuel outlet ofthe fuel inlet pipe. Since the arm presses the valve element against theseat, the check valve ensures a sufficient seal in the closed position.

The second check valve of the above configuration is not attached to thefuel inlet pipe, but is directly attached to the inner wall of the mainbody by the fixation member. This arrangement enables the check valvenot to be tubular, but flat in shape, thereby simplifying the structureof the fixation member. The fixation member, which is formed to supportthe thin valve plate, needs a relatively thin wall thickness.

The second check valve includes the thin valve plate and does notrequire any spring to move the valve plate between the open position andthe closed position or any mechanism for setting the spring. Thisarrangement simplifies the structure of the check valve.

In accordance with one preferred embodiment of the present invention,the valve element is formed in a disc shape, and the arm is arranged ona circumference of the valve element.

In accordance with another preferred embodiment of the presentinvention, the fixation member has a circular protection step, whichsurrounds a circumference of the seat and protrudes inward in the mainbody to protect the valve element. The circular protection stepeffectively prevents the elastic thin valve plate from being deformedduring attachment of the check valve to the inner wall of the main body.

In one method for attaching the valve plate to the fixation member, thevalve plate has a claw obtained by cutting and bending part of theattachment. The fixation member has an engagement recess, which receivesthe attachment of the valve plate inserted therein, and an engagementaperture, which is formed in the vicinity of the engagement recess.Insertion of the attachment into the engagement recess causes the clawto be fit in the engagement aperture so that the valve plate is attachedto the fixation member.

In another method for attaching the valve plate to the fixation member,the attachment of the valve plate is welded and fixed to the fixationmember.

In still another method for attaching the valve plate to the fixationmember, the attachment has a lower extension bent to surround acircumference of the fixation member. In this application, theattachment is attached to the fixation member by the lower extension.

In accordance with still another preferred embodiment of the presentinvention, the fixation member has an attachment pawl, which engageswith the inner wall of the main body to attach the fixation member tothe main body, and a valve pawl, which engages with the attachment ofthe valve plate to attach the valve plate to the fixation member. Thisarrangement enables the fixation member to be attached to the main bodywithout welding so that the main body may be made of a resin.

The present invention is also directed to a second fuel tank including amain body, in which fuel is kept, and a fuel inlet pipe, which isconnected to the main body and through which a supply of fuel is flowninto the main body. The second fuel tank is provided with a check valvethat is attached to an inner wall of the main body and is connected to afuel conduit of the fuel inlet pipe. The check valve prevents liquidfuel and fuel vapor in the main body from flowing through the fuel inletpipe and being released to outside. The check valve is opened by a flowof fuel in the fuel inlet pipe to allow the flow of fuel to beintroduced into the main body. The check valve includes a fixationmember that has a seat designed to surround a fuel outlet of the fuelinlet pipe and is formed to fix the check valve to the inner wall of thefuel tank; and a valve plate that is attached to the fixation member andis movable between an open position and a closed position to open andclose the fuel outlet. The valve plate has a valve element that isseated on the seat in the closed position and removed from the seat inthe open position to close and open the fuel outlet; an arm linked withthe valve element; and an attachment that is connected with the arm andis formed to attach the valve disc to the casing. The valve element, thearm, and the attachment are integrally formed from a thin plate havingelasticity. The arm is designed to press the valve element against theseat to cause the valve element to be seated on the seat in the closedposition. The arm causes the valve element to be removed from the seatand thereby sets the valve element in the open position when the valveelement receives a pressure of the flow of fuel applied thereto duringfueling.

The arrangement of the second fuel tank facilitates the attachment ofthe second check valve to the fuel tank.

These and other objects, features, aspects, and advantages of thepresent invention will become more apparent from the following detaileddescription of the preferred embodiments with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a fuel tank of an automobile with acheck valve of a first embodiment according to the present invention;

FIG. 2 is a sectional view illustrating the check valve of theembodiment in a closed position;

FIG. 3 is a sectional view illustrating the check valve of theembodiment in an open position;

FIG. 4 illustrates the check valve of the embodiment from theperspective of an arrow IV of FIG. 2;

FIG. 5 shows a fixation plate of the check valve having a modifiedstructure;

FIG. 6 is a partial view schematically illustrating another fuel tank ofan automobile with a check valve of a second embodiment according to thepresent invention;

FIG. 7 is a plan view showing the check valve of the second embodimentfrom the presence of an arrow VIII of FIG. 6;

FIG. 8 is a sectional view illustrating the check valve of the secondembodiment, taken along on the line VIII—VIII in FIG. 7;

FIG. 9 is a decomposed sectional view illustrating the check valve ofthe second embodiment before being assembled;

FIG. 10 shows a process of attaching a valve plate to a fixation member;

FIG. 11 is a plan view illustrating another check valve according to amodification of the second embodiment;

FIG. 12 is a sectional view illustrating the check valve of FIG. 11,taken on the line XII—XII in FIG. 11;

FIG. 13 is a decomposed sectional view illustrating the check valve ofFIG. 11 before being assembled;

FIG. 14 is a plan view illustrating another check valve according toanother modification of the second embodiment;

FIG. 15 is a sectional view illustrating the check valve of FIG. 14,taken on the line XV—XV in FIG. 14;

FIG. 16 is a decomposed sectional view illustrating the check valve ofFIG. 14 before being fixed to a side wall of a main body;

FIG. 17 is a plan view illustrating another check valve according toanother modification of the second embodiment;

FIG. 18 is a sectional view illustrating the check valve of FIG. 17,taken on the line XVm—XVm in FIG. 17

FIG. 19 is a decomposed sectional view illustrating the check valve ofFIG. 17 before being attached to a side wall of a main body;

FIG. 20 is a decomposed perspective view illustrating the check valve ofFIG. 17;

FIG. 21 is a side view schematically illustrating a check valve of athird embodiment according to the present invention; and

FIG. 22 is a sectional view showing the check valve of FIG. 21.

DESCRIPTION OF THE CURRENTLY PREFERRED EMBODIMENTS OF THE PRESENTINVENTION

FIG. 1 schematically illustrates a fuel tank 10 of an automobile.Referring to FIG. 1, the fuel tank 10 includes a main body 12, in whichfuel is kept, and a fueling mechanism 20 that functions as the fuelinlet pipe of the present invention to fill the main body 12 with asupply of fuel. The main body 12 is made of zinc-plated steel andincludes an upper tank section 13 and a lower tank section 14, which arejoined with each other to form an integral body. The fueling mechanism20 includes an inlet lower pipe 22 welded to a side wall 14 a of thelower tank section 14, an inlet hose 24 having one end open to receive afirst end of the inlet lower pipe 22 fitted therein, an inlet fillerpipe 26 fit in the second end of the inlet hose 24, and a filler cap(not shown) covering a filler opening of the inlet filler pipe 26.

The second end of the inlet lower pipe 22 forms a flange 22 a, which isattached to an opening 14 b formed in the side wall 14 a of the lowertank section 14. A check valve 30 is attached to an inner wall of thelower tank section 14 to face an outlet 22 b defined by the second endof the inlet lower pipe 22. The check valve 30 is set in an openposition during fueling and is otherwise kept in a closed position. Afuel cut-off valve 28 is disposed in an upper portion of the main body12. The fuel cut-off valve 28 is connected to a canister (not shown) viaa conduit 28 a.

In the fueling mechanism 20 of the above configuration, when a supply offuel is fed from a filler gun FG to the inlet filler pipe 26 with thefiller cap opened, the supply of fuel flows through the inlet hose 24and the inlet lower pipe 22 to the check valve 30 and opens the checkvalve 30 to flow into the main body 12. The check valve 30 is kept inthe closed position, except during fueling. Even when the filler cap isremoved accidentally, the check valve 30 thus effectively prevents theliquid fuel and fuel vapors in the main body 12 from flowing back andbeing released to the outside.

The following describes the structure and the operation of the checkvalve 30 in detail. FIG. 2 is a sectional view illustrating the checkvalve 30 in the closed position; FIG. 3 is a sectional view illustratingthe check valve 30 in the open position; and FIG. 4 illustrates thecheck valve 30 seen from an arrow IV of FIG. 2. Referring to FIGS. 2through 4, the check valve 30 has a casing 32 that defines a valve chest31 connecting with a fuel conduit 22 c of the inlet lower pipe 22, afixation plate 37, a valve disc 40, and a spring 50 as primaryconstituents.

The casing 32 includes a cylindrical side wall 32 a and defines thevalve chest 31 therein. One end of the side wall 32 a forms a flange 32b where the fixation plate 37 is inserted and attached. The fixationplate 37 is a doughnut-shaped plate having an inner hole 37 b, as shownin FIG. 4. The fixation plate 37 is made of zinc-plated steel like themain body 12 and has three handles 37 a obtained by bending thecircumference of the fixation plate 37 at three different places. Thethree handles 37 a are held by fixtures for attaching the check valve 30to the main body 12 as discussed later. The circumference of the innerhole 37 b in the fixation plate 37 is inserted into the flange 32 b ofthe casing 32 and is thereby integrated with the casing 32. The fixationplate 37 is designed to have a smooth plane that comes into closecontact with the side wall 14 a of the main body 12, and is attached tothe side wall 14 a of the main body 12 by spot welding at three weldingpoints 37 c. The side wall 14 a of the main body 12 is inclined relativeto the vertical direction so that the check valve 30 is arrangedobliquely upward.

Referring back to FIG. 2, the other end of the casing 32 forms a fueloutlet 33 that is opened and closed by the valve disc 40. The valve disc40 has a valve element 41 and a shaft 42 formed integrally with thevalve element 41. The valve element 41 has a seating portion 41 a, whichis seated on and removed from a mating seat 33 a of the fuel outlet 33to close and open the fuel outlet 33. A flare portion 41 b is formedintegrally with the seating portion 41 a. The flare portion 41 b flaresin order to cause the supply of fuel flowing through the valve chest 31to be ejected from the fuel outlet 33 to a wider area.

The valve disc 40 is supported by a valve support 34 and three linkageelements 35 of the casing 32 via the shaft 42 thereof to be movablebetween the open position and the closed position. The three linkageelements 35 and the valve support 34 are disposed in the valve chest 31of the casing 32 to support the valve disc 40. The three linkageelements 35 are arranged radially at the intervals of 120 degrees, andthe flow of fuel passes through the spaces between the adjoining linkageelements 35. The valve support 34 is integrated with a central joint ofthe three linkage elements 35 and has a valve support aperture 34 a. Theshaft 42 of the valve disc 40 passes through the valve support aperture34 a of the valve support 34 so that the valve disc 40 is supported in amovable manner by the casing 32. A free end of the shaft 42 forms a snapfit 42 a, which engages with a spring stopper 43 in an elastic manner.

The spring 50, which presses the valve disc 40, is set on the shaft 42and spans between the valve support 34 and the spring stopper 43. Theassembly of the check valve 30 inserts the shaft 42 of the valve disc 40into the valve support aperture 34 a of the valve support 34, sets thespring 50 on the shaft 42 of the valve disc 40, and causes the snap fit42 a of the shaft 42 to engage with the spring stopper 43.

In the closed position, the check valve 30 of the above structureeffectively prevents the liquid fuel and fuel vapors in the main body 12from flowing back through the inlet lower pipe 22 and being released tothe outside. During fueling, the supply of fuel, which is fed throughthe inlet filler pipe 26, the inlet hose 24, and the inlet lower pipe22, flows through the fuel conduit 22 c into the valve chest 31 of thecheck valve 30 to reach the valve disc 40. When the force of flow offuel applied to the valve disc 40 exceeds the pressing force of thespring 50, the valve disc 40 moves to its open position to enable theflow of fuel to enter the main body 12. The flare portion 41 b of thevalve disc 40 spreads out the flow of fuel, which is accordingly sprayedover a wide space in the main body 12. The flow of cold fuel lowers thesaturated vapor pressure in the main body 12 and prevents the fuelvapors from being released to the outside during fueling.

The following describes a process of attaching the check valve 30 to theinner wall of the main body 12. While the upper tank section 13 and thelower tank section 14 are not joined with each other, the lower tanksection 14 is positioned on a work table (not shown). The three handles37 a of the fixation plate 37 are held by the fixtures, and the checkvalve 30 is set on the outlet 22 b of the inlet lower pipe 22. The threewelding points 37 c arranged between the adjoining handles 37 a on thecircumference of the fixation plate 37 are spot welded to the lower tanksection 14 so that the check valve 30 is attached to the inner wall ofthe main body 12.

Since the fixation plate 37 of the check valve 30, which is attached tothe main body 12 in the above manner, is inserted in the end of thecasing 32. This arrangement ensures a sufficient seal between thefixation plate 37 and the casing 32. The smooth plane of the fixationplate 37 is in close contact with the inner wall of the main body 12 byspot welding to ensure a sufficient seal between the fixation plate 37and the main body 12. The fixation plate 37 accordingly enables the mainbody 12 to be sufficiently sealed from the fueling mechanism 20 and fromthe outside. This arrangement makes any special sealing elements, suchas O rings, unrequited, thereby desirably reducing the total number ofparts.

Since the fixation plate 37 is inserted into and thereby integrated withthe casing 32 in the course of injection molding, the integrated partsimplifies the process of attachment of the check valve 30 to the mainbody 12.

The configuration of the embodiment discussed above may be modified,changed, or altered in various ways without departing from the scope orspirit of the main characteristics of the present invention.

By way of example, FIG. 5 shows the fixation plate 37 having a modifiedstructure. A ring-shaped seal projection 32 d formed around the wholecircumference of the flange 32 b protrudes from an end plane of theflange 32 b. The seal projection 32 d is designed to allow elasticdeformation. The seal projection 32 d is pressed against and therebyjammed to the side wall 14 a of the main body 12 to enhance the seal ofthe main body 12 from the fuel conduit 22 c.

FIG. 6 is a partly omitted view schematically illustrating fuel tank 110of an automobile of a second embodiment according to the presentinvention. Referring to FIG. 6, the fuel tank 110 includes a main body112, in which fuel is kept, and a fueling mechanism 120 that functionsas the fuel inlet pipe of the present invention to fill tie main body112 with a supply of fuel. The main body 112 is made of a metal andincludes an upper tank section 113 and a lower tank section 114, whichare joined with each other via flanges 113 a and 114 a, welded to forman integral body. The fueling mechanism 120 includes an inlet lower pipe122 welded to a side wall 115 of the lower tank section 114, a bellowsinlet hose 124 having one end open to receive a first end of the inletlower pipe 122 fit therein, an inlet filler pipe 126 fit in the secondend of the inlet hose 124, and a filler cap 128 covering a filleropening of the inlet filler pipe 126.

The second end of the inlet lower pipe 122 is positioned at an opening115 a of the side wall 115 and welded to the outer surface of the sidewall 115 via a flange 122 a. A check valve 130 is then positioned at theopening 115 a and is attached to the inner surface of the side wall 115.The check valve 130 is set in an open position during fueling and isotherwise kept in a closed position.

In the fueling mechanism 120 of the above configuration, when a supplyof fuel is fed from a filler gun (not shown) to the inlet filler pipe126 with the filler cap 128 opened, the supply of fuel flows through theinlet hose 124 and the inlet lower pipe 122 to the check valve 130 andopens the check valve 130 to flow into the main body 112. The checkvalve 130 is kept in the closed position, except during fueling. Evenwhen the filler cap 128 is removed accidentally, the check valve 130thus effectively prevents the liquid fuel and fuel vapors in the mainbody 112 from flowing back and being released to the outside.

The following describes the structure and the operation of the checkvalve 130 of the second embodiment in detail. FIG. 7 is a plan viewshowing the check valve 130 seen from an arrow vm of FIG. 6; FIG. 8 is asectional view illustrating the check valve 130, taken on the lineVIII—VIII in FIG. 7; and FIG. 9 is a decomposed sectional viewillustrating the check valve 130 before being assembled. Referring toFIGS. 7 through 9, the check valve 130 includes a disc-shaped metalfixation member 132 and a valve plate 140 that is attached to one end ofthe fixation member 132 and is movable between an open position and aclosed position to open and close a valve opening 133 a.

The fixation member 132 has an attachment body 133 welded to the sidewall 115 of the main body 112 and an engagement 134 protruded from oneend of the attachment body 133. The attachment body 133 has the valveopening 133 a, which communicates with the opening 115 a of the mainbody 12. The valve opening 133 a has an arc shape defined by a linearend 133 c as chord, as shown by the dotted line in FIG. 7. Thecircumference of the valve opening 133 a forms a seat 133 b on which thevalve plate 140 is seated. A circular protection step 133 d is formedaround the seat 133 b, except where the engagement 134 protrudes inwardin the main body 112. The circular protection step 133 d forms a ridgeto protect the valve plate 140 as discussed later.

The engagement 134 has an L-shape and protrudes from one end of theattachment body 133. The engagement 134 has an engagement recess 134 a,which is defined by the upper surface of the attachment body 133 and theL-shaped portion of the engagement 134, which receives one end of thevalve plate 140 therein. An engagement aperture 134 b is formed in theattachment body 133 and located below the L-shaped portion of theengagement 134 in order to prevent the valve plate 140 from slippingoff.

The following describes the detailed structure of the valve plate 140.As shown in FIG. 7, the valve plate 140, manufactured by press cutting athin plate, includes a valve element 141, an arm 142, and an attachment144, which are integrally formed as a leaf spring. The valve element 141has substantially the same shape as the contour of the seat 133 b on thecircumference of the valve opening 133 a, and is designed to be seatedon and removed from the seat 133 b to close and open the valve opening133 a. The valve element 141 includes a linear portion 141 a and an arcportion 141 b. The semicircular arm 142 is arranged on the circumferenceof the valve element 141 across a predetermined space S. The arm 142 isintegrated with the valve element 141 on both ends of the valve element141. In FIG. 8, the solid line shows the valve plate 140 in the closedposition, whereas the one-dot chain line shows the valve plate 140 inthe open position.

The valve plate 140 also has the attachment 144, which is a rectangularpiece that extends outward from the center portion of the arm 142. Theattachment 144 has a U-shaped claw 144 a, which is obtained by cuttingand bending a substantial center of the attachment 144. The attachment144 fits in and is supported by the engagement 134 of the fixationmember 132. FIG. 10 shows a process of attaching the valve plate 140 tothe fixation member 132. The attachment 144 of the valve plate 140 isinserted into the engagement recess 134 a of the fixation member 132. Atthis moment, the U-shaped claw 144 a is compressed by the engagementrecess 134 a and is thereby fit into the engagement aperture 134 b. Thisarrangement causes one end of the valve plate 140 to be securelyattached to the fixation member 132, as shown in FIG. 8.

The operation of the check valve 130 is described in detail. Duringfueling, a supply of fuel, which is fed through the filler opening ofthe fueling mechanism 120, flows through the inlet lower pipe 122 toreach a fuel outlet 122 b and presses the valve element 141 of the valveplate 140. Since the attachment 144 of the valve plate 140 is attachedto the engagement 134 of the fixation member 132 as discussed above (asshown by the one-dot chain line in FIG. 8), the flow of fuel presses thevalve element 141 and applies a force of inclining the arm 142 to openthe valve opening 133 a. This enables the supply of fuel to flow intothe main body 112. When the force applied to the valve element 141 bythe flow of fuel becomes smaller than the pressing force by the arm 142,the valve element 141 is not caught by the seat 133 b by the function ofthe linear portion 141 a of the valve element 141, but is smoothlyseated on the seat 133 b to close the valve opening 133 a.

Since the valve element 141 of the valve plate 140 is joined with theattachment 144 via the narrow arm 142, the valve element 141 inclinesthe arm 142 and opens the valve opening 133 a. This arrangement ensuresa relatively wide opening space of the valve opening 133 a and enablesthe supply of fuel to flow through the passage of the relatively largearea

The following describes the process of attaching the check valve 130 tothe main body 112. As shown in FIG. 10, the attachment 144 of the valveplate 140 is pressed into the engagement recess 134 a of the engagement134. The claw 144 a is then compressed in the engagement recess 134 aand fit into the engagement apertures 134 b. The valve plate 140 is thusintegrally joined with the fixation member 132. The claw 144 a functionsto prevent the valve plate 140 from slipping off the fixation member132.

While the upper tank section 113 and the lower tank section 114 are notjoined with each other, the fixation member 132 of the check valve 130is positioned at the opening 115 a of the side wall 115 of the lowertank section 114. In this state, the fixation member 132 is spot weldedto the sidewall 115. The spot welding is carried out at three pointsthat are shown as spot welding points Wd1 in FIG. 7 and arranged at aninterval along the circumference of the fixation member 132. This causesthe check valve 130 to be securely attached to the side wall 115 of thelower tank section 114. The main body 112 is then formed by welding theupper tank section 113 to the lower tank section 114 via the flanges 113a and 114 a.

The check valve 130 of this embodiment has the following effects;

(1) Since the check valve 130 is securely attached to the side wall 115by simply welding the fixation member 132 integrated with the valveplate 40 to the side wall 115 of the main body 112, the arrangement ofthe embodiment facilitates the process of attachment.

(2) Since the check valve 130, which mainly consists of two parts, thefixation member 132 and the valve plate 140, this structure reduces therequired number of parts and thereby lowers the manufacturing cost,compared with the prior art check valve.

(3) Since the circular protection step 133 d, which is formed tosurround the valve plate 140 is protruded inward from the plane of thevalve plate 140 in the main body 112, this arrangement effectivelyprevents the valve plate 140 from being touched and deformed duringwelding the fixation member 132 or during the delivery of the checkvalve 130. This arrangement also attains the secure seal of the valveplate 140.

(4) The valve plate 140 is securely attached to the fixation member 132simply by pressing the attachment 144 of the valve plate 140 into theengagement recess 134 a of the fixation member 132. The claw 144 a isfit in the engagement aperture 134 b, in order to prevent the valveplate 140 from slipping off the fixation member 132.

(5) Since the spring, which is formed by the narrow arm 142 generates aforce applied in the valve-closing direction, enables a smallvalve-opening force to be sufficient for the valve opening operation,while ensuring the high sealing properties.

FIGS. 11 through 13 show a check valve 130B as one modification of thesecond embodiment. FIG. 11 is a plan view showing the check valve 130B;

FIG. 12 is a sectional view showing the check valve 130B, taken on theline XII—XII in FIG. 11; and FIG. 13 is a sectional view showing thecheck valve 130B before being assembled. In the check valve 130B of thismodified example, a valve plate 140B has a different attachmentstructure from that of the valve plate 140 shown in FIG. 6. Anattachment 144D of the valve plate 140B has a grip 144Bc, which is bentto a U shape to receive an end of a fixation member 132B. The grip 144Bchas a lower extension 144Bb, which is partly cut and bent to form a claw144Ba.

The process of attaching the valve plate 140B to the fixation member132B is described briefly with reference to FIG. 13. The end of thefixation member 132B is pressed into the grip 144Bc of the valve plate140B. This causes the grip 144Bc of the valve plate 140B to grip the endof the fixation member 132B. The claw 144Ba is pressed down and fittedinto an engagement apertures 134Bb of the fixation member 132B. Thiscauses the valve plate 140B to be securely attached to the fixationmember 132B. The check valve 130B, which is the integral body of thevalve plate 140B and the fixation member 132B, is attached to the mainbody 112 by welding the circumference of the fixation member 132B to theside wall 115 of the main body 112. In the check valve 130B of thismodified structure, the lower extension 144Bb is held between the sidewall 115 and the fixation member 132B. The check valve 130B is thussecurely attached to the main body 112, even when the valve plate 140Breceives a relatively large force generated by the flow of fuel.

FIGS. 14 through 16 show a check valve 130C as another modification ofthe second embodiment. FIG. 14 is a plan view showing the check valve130C; FIG. 15 is a sectional view showing the check valve 130C, taken onthe line XV—XV in FIG. 14; and FIG. 16 is a sectional view showing thecheck valve 130C before being attached to the side wall 115 of the mainbody 112. In the check valve 130C of this modified example, a valveplate 140C has a different attachment structure from that of the valveplate 140 shown in FIG. 6. The valve plate 140C has an attachment 144Con one end thereof, which is welded to a fixation member 132C. Namelythe valve plate 140C is attached to the fixation member 132C by spotwelding the attachment 144C of the valve plate 140C to the fixationmember 132C. The spot welding point is shown as Wd2 in FIG. 14. Thecheck valve 130C, which is the integral body of the valve plate 140C andthe fixation member 132C, is attached to the main body 112 by weldingthe circumference of the fixation member 132C to the side wall 115 ofthe main body 112. It is preferable to use a positioning member in orderto position the valve plate 140C relative to the fixation member 132Cbefore the valve plate 140C is welded to the fixation member 132C.

FIGS. 17 through 20 show a check valve 130D as still anothermodification of the second embodiment. FIG. 17 is a plan view showingthe check valve 130D; FIG. 8 is a sectional view showing the check valve130D, taken on the line XVIII—XVIII in FIG. 17; FIG. 19 is a sectionalview showing the check valve 130D before being attached to the side wall115 of the main body 112; and FIG. 20 is a decomposed perspective viewshowing the check valve 130D. The check valve 130D has an attachmentstructure, which is applicable to the main body 112 made of a resin. Thecheck valve 130D has a fixation member 150 with a valve opening 150 aand a valve plate 140D attached to the fixation member 150. The fixationmember 150 is made of a synthetic resin having a fuel resistance, forexample, polyacetal or polyamide. The fixation member 150 has a circularattachment 152 and a rectangular support 154, which are formedintegrally. The support 154 extends outward from one end of theattachment 152 to support the valve plate 140D. A circular protectionstep 156 is formed around the attachment 152 and the support 154. Thecircular protection step 156 protrudes downward (in the drawing) toprotect the valve plate 140D.

Three attachment pawls 158 protrude upward (in the drawing) from theinner circumference of the attachment 152 along the valve opening 150 aand are arranged at intervals of 120 degrees. The attachment pawls 158engage with a circumferential part 115 b of an opening 115 a formed inthe side wall 115 so that the check valve 130D is securely attached tothe side wall 115 of the main body 112. The support 154 has two valvepawls 159 that are protruded downward (in the drawing) to hold the valveplate 140D. The valve plate 140D has a valve attachment 145D. The valveattachment 145D has an engagement aperture 145Da, in to which the valvepawls 159 are fitted.

The process of attaching the valve plate 140 to the fixation member 150is briefly described with reference to FIGS. 19 and 20. The valve pawls159 of the fixation member 150 are pressed into the engagement aperture145Da of the valve plate 140D. The valve pawls 159 are expanded at aposition exceeding the engagement aperture 145Da to hold the valve plate140D. This arrangement enables the valve plate 140D to be securely heldby the fixation member 150.

The check valve 130D assembled in the above manner is attached to themain body 112 by inserting the attachment pawls 158 of the fixationmember 150 into the opening 115 a of the side wall 115 of the main body112 and making the attachment pawls 158 engage with the circumferentialpart 115 b of the opening 115 a.

The configuration of the check valve 130D enables the resin fixationmember 150 to be securely attached to the main body 112, which is alsomade of a resin and does not allow welding. The valve plate 140D ispositioned by the valve pawls 159 at the support 154 of the fixationmember 150 and securely attached to the fixation member 150.

FIG. 21 is a side view illustrating a check valve 160 of a thirdembodiment according to the present invention, and FIG. 22 is asectional view showing the check valve 160. Referring to FIGS. 21 and22, the check valve 160 is welded and attached to a main body (notshown) via a metal attachment plate 170, which is mounted on a lower endof a tubular casing 162. The check valve 160 includes the casing 162,the attachment plate 170, and a valve plate 180. The valve plate 180 hasa valve element 181, an arm 182, and an attachment 183. The tubularcasing 162 is made of a resin and has a valve chest 162 a. A flange 163is formed on the lower end of the casing 162 to receive the metalattachment plate 170 inserted therein. The upper end of the casing 162has a fuel outlet 166, which is opened and closed by the valve plate180. A circular protecting projection 164 is also formed on the upperend of the casing 162 to protect the valve plate 180. A valve support165 with a support recess 165 a is formed on an upper side portion ofthe casing 162. The valve support 165 holds the attachment 183 of thevalve plate 180 and supports the whole valve plate 180 via a claw 183 afit in the support recess 165 a. The check valve 160, which is theintegral body of the valve plate 180, the tubular casing 162, and theattachment plate 170, are welded and attached to the main body.

The present invention is not restricted to the above embodiments ortheir modifications, but there may be many other modifications, changes,and alterations without departing from the scope or spirit of the maincharacteristics of the present invention. Some examples of possiblemodification are given below.

(1) The valve element of the valve plate may have any shapecorresponding to the shape of the fuel conduit, for example, a circle ora sector, which is a section of a circle, as well as a polygon liketriangle or rectangle.

(2) In the above embodiments, the valve plate is made of stainlesssteel, but may be made of any material having spring characteristics,for example, a resin.

The scope and spirit of the present invention are limited only by theterms of the appended claims.

What is claimed is:
 1. A check valve attached to an inner wall of a mainbody of a fuel tank, in which fuel is kept, and arranged proximate to afuel outlet of a fuel inlet pipe, through which a supply of fuel isejected into said main body, said check valve comprising: a fixationmember having a seat designed to surround said fuel outlet and formed toattach said check valve to said inner wall of said fuel tank; and avalve plate attached to said fixation member and movable between an openposition and a closed position to open and close said fuel outlet,wherein said valve plate comprises a valve element seated on said seatin a closed position and removed from said seat in an open position toclose and open said fuel outlet; an arm linked with said valve element;and an attachment connected with said arm and formed to attach saidvalve plate to said casing, wherein said valve element, said arm, andsaid attachment are integrally formed from a thin plate havingelasticity, and said arm to presses said valve element against said seatto cause said valve element to be seated on said seat in said closedposition, said arm causing said valve element to be removed from saidseat and thereby setting said valve element in said open position whensaid valve element receives a pressure of a flow of fuel applied theretoduring fueling.
 2. A check valve according to claim 1, wherein saidvalve element has a disc shape, and said arm disposed on a circumferenceof said valve element.
 3. A check valve according to claim 1, whereinsaid fixation member has a circular protection step, which surrounds acircumference of said seat and protrudes inward in said main body toprotect said valve element.
 4. A check valve according to claim 1,wherein said attachment has a claw obtained by cutting and bending partof said attachment, said fixation member has an engagement recess, whichreceives said attachment of said valve plate inserted therein, and anengagement aperture, which is formed proximate to said engagement recesssuch that insertion of said attachment into said engagement recesscauses said claw to be fit in said engagement aperture, so that saidvalve plate is attached to said fixation member.
 5. A check valveaccording to claim 1, wherein said attachment has a lower extension bentto surround a circumference of said fixation member, said attachmentbeing attached to said fixation member by said lower extension.
 6. Acheck valve according to claim 1, wherein said attachment is welded andattached to said fixation member.
 7. A check valve according to claim 1,wherein said fixation member has an attachment pawl, which engages withsaid inner wall of said main body to attach said fixation member to saidmain body, and a valve pawl, which engages with said attachment of saidvalve plate to attach said valve plate to said fixation member.
 8. Acheck valve according to claim 7, wherein said fixation member is madeof a resin.
 9. A fuel tank, comprising: a main body, in which fuel iskept; and a fuel inlet pipe connected to said main body and throughwhich a supply of fuel flows into said main body, said fuel tankprovided with a check valve attached to an inner wall of said main bodyand connected to a fuel conduit of said fuel inlet pipe, said checkvalve preventing liquid fuel and fuel vapors in said main body fromflowing through said fuel inlet pipe and being released to the outside,said check valve opened by a flow of fuel in said fuel inlet pipe toallow flow of fuel to be introduced into said main body, wherein saidcheck valve comprises: a fixation member having a seat designed tosurround a fuel outlet of said fuel inlet pipe and formed to attach saidcheck valve to said inner wall of said fuel tank; and a valve plateattached to said fixation member and movable between an open positionand a closed position to open and close said fuel outlet, wherein saidvalve plate comprises: a valve element seated on said seat in saidclosed position and removed from said seat in said open position toclose and open said fuel outlet; an arm linked with said valve element;and an attachment connected to said arm and formed to attach said valvedisc to said casing, wherein said valve element, said arm, and saidattachment are integrally formed from a thin plate having elasticity,said arm pressing said valve element against said seat to cause saidvalve element to be seated on said seat in the closed position, said armcausing said valve element to be removed from said seat and therebysetting said valve element in said open position when said valve elementreceives a pressure of the flow of fuel applied thereto during fueling.10. A fuel tank according to claim 9, wherein said fixation member iswelded and attached to said inner wall of said main body.